Plural shielded atomizing nozzles in thermal cracking of liquid hydrocarbons



Peb. 7, 1967 I-I SCHMIDT ETAI. 3,303,103

PLURAL SHIELDED ATOMIZING NOZZLES IN THERMAL CRACKING 0F LIQUID HYDROCARBONS Filed Jan. 6, 1964 2 Sheets-Sheet 1 INVENTOR5 HERBERT SCHM/DT WALTER JA HNEN TZ ALFRED CHM/DT BY (fm ATTORNEY Feb. 7, 1967 H SCHMIDT ETAL 3,303,103

PLURAL SHIELDED ATOMIZING NOZZLES IN THERMAL CRACKING OF LIQUID HYDROCARBONS Filed Jan. 6, 1964 2 Sheets-Sheet 2 INVENTORS HERERT SCHMIDT WALTER c/AHNENTZ ALFRED SCHMIDT ATTORNEY United States Patent C) s claims. (cl. 19a-116) This invention relates to a reactor for the thermal decomposition of liquid hydrocarbons, and more particularly to a type of reactor in which improved yields of unsaturated hydrocarbons such as acetylene and ethylene are produced.

The production of unsaturated hydrocarbons,` such as acetylene and ethylene, by the thermal decomposition of liquid hydrocarbons at elevated temperatures isvnow well known. However, the previous processes have presented numerous difiiculties, primarily because of the relatively low yields of the desired products obtained from large reactors.

One of the procedures known before involves the thermal cracking under acetylene forming conditions in which the liquid hydrocarbons are atomized by an amount of oxygen insufficient for complete combustion of the hydrocarbons and in which the cracking and cornbustion gases are quenched with the same liquid hydrocarbons atomized in excess. Operating the cracking process in this way, the amount of acetylene present is found to be largely dependent on the amount of oxygen used and the degree of cracking attained. Since the binary nozzles used for the atomisation of the liquid hydrocarbons by the oxygen inside the reactor are designed for a certain maximum feeding rate, it becomes necessary when high production is required that the installation should either contain a plurality of similar reactors for operation in parallel, or that larger nozzles with higher feeding rates and proportionally larger reactors be used, or that use be made of larger reactors each containing a larger number of nozzles. However, the use of a large number of small reactors involves greatly increased costs of installation, and in addition are more difficult to operate satisfactorily. The use of larger nozzles with larger reactors in order to obtain higher production of the desired products from individual units has likewise not been satisfactory because of the fact that when the size of the conical spray of injected reactants is increased the size of the reaction chamber must also be increased, making it more difficult to control the reactions therein.

In the past, the best solution to the above problems has been attained by the use of several injection nozzles in parallel in a single reactor. Even in this case, however, serious operating difficulties have been encountered in practice. Uniform ignition of the multiple injection nozzles has been found almost impossible. When successive ignition of the injection nozzles is attempted, the previously ignited nozzles frequently are extinguished by the subsequently ignited nozzles. Explosions even take place in the reactor if the oxygen concentration in some sections thereof becomes too high because of non-uniform ignition. Uncontrollable surging across cones of injected reactants in which the reaction occurs, as well as the unavoidable gaseous vortices around the orifices of the nozzles, interfere with the desired reaction process and result in reduced yields of acetylene and at the same time produce an increased amount of undesired carbon and carbon monoxide. Operation of the multiple nozzle reactors has generally only been found possible when the nozzles were well spaced from each other and each nozzle has its own ignition system. Such reactor systems, however, have required reactors lof prohibitive dimensions.

It has now been found that the difficulties experienced in previous systems can ybe readily overcome by a new and novel arrangement of the injection nozzles whereby a plurality of nozzles suitable for the simultaneous atomization of liquid hydrocarbons by the oxygen inside the reactor are positioned in the upper portion of the reactor, preferably in a single plane and suitably shielded from each other, as hereinafter described. With such an arrangement liquid hydrocarbons atomized by oxygen in an amount insufiicient for complete combustion of the hydrocarbons can be satisfactorily cracked under acetylene forming conditions by incomplete combustion, with the formation of improved yields of unsaturated hydrocarbons, such as acetylene and ethylene.

In a preferred arrange-ment of our invention, the orifices of the nozzles are shielded from each other by separating walls, the average distance of which from the orifces, expressed in millimeters, is from 0.7 to 2.5 times the amount of oxygen discharged from the nozzle in Nm.3/h., while the height of the separating walls above the level of the orifices is from 0.5 to 5 times the average distance of the orifice from the separating walls.

It has been found that if these separating walls are too low they will not offer sufficient protection to the atomized cones, whereas if they are too high the flames will bounce back and the burning inside the walls will cause the formation of soot and incrustations in the regions around the nozzle orifices.

Depending upon the dimensions of the separating walls, it is sometimes `advantageous to cool the latter by circulating through them a suitable cooling fluid. Usually, however, sufficient cooling of the separating walls is obtained by the cooling effect of the hydrocarbons sprayed in excess, provided care is taken to have the separating walls of such deminsions that droplets of the hydrocarbons reach them in sufficient numbers.

The form of the hollow space formed about the nozzles by the separating walls can be either round, oval, or polygonal, and in the vertical direction they can be either of uniform cross-section or they can be tapered in the upward or downward direction, depending on the particular operating conditions.

A particularly advantageous arrangement has been found to be one in which the walls form a honeycomb structure in which the central nozzle is surrounded by walls forming a hexagon. Such a construction permits efficient utilization of a minimum of space and renders further cooling of the walls generally unnecessary since the walls will then be cooled from both sides by atomize liquid hydrocarbons. l

The improved results obtained by the use of our new and improved form of reactor are illustrated by specific reactors described below. It should be understood, however, that the particular forms described are for purposes of illustrating our improved reactor and are not to be regarded as limitative in any manner since various modi fications of our new reactor can be satisfactorily used without departing from the basic concept ofA our invention which is covered by the appended claims.

Examples ln the three specific modifications of reactors described below the specified amounts of a crude oil having a boiling point .rangeof from 50 to 450 C. was atomized with oxygen in the ratio of 1 kg. of oxygen t-o 4 kg. of crude oil, identical mixtures of reactants being used in all three reactors.

Reactor No. 1

The first reactor, illustrated in FIGURE 1 of the attached drawing, had a diameter of 60 cm. and a height of 115 cm. The crude oil from a conduit 3 was atomized by 40 Nm3/h. oxygen from conduit 4 inthe atomizing nozzle 2. A portion of the atomized oil was reacted with the oxygen under acetylene forming conditions fby incomplete combustion to produce gaseous reaction products which were removed by conduit 6, while the remainder of the oil which had served to cool the reaction products was removed through conduit 5. After separation of the entrained oil vapors from the gaseous reaction products removed through conduit 6 there remained in the resulting mixture 6.3% by volume of acetylene and 6.4% by volume of ethylene. In the production of 1 kg. of acetylene plus ethylene mixture 3.3 kg. of oxygen were consumed. The cross-sectional loading of the reactor amounted to 1.4 Nm3/h. oxygen per dim?, the volume loading being 0.12 Nm3/h. oxygen per liter.

Reactor N o. 2

Reactor No. 2, illustrated in FIGURE 2a, had a diameter of 40 cm. and a height of 80 cm. In the top of the reactor were mounted four atomizing nozzles, arranged as shown in FIGURE 2b, through which passed the oil and oxygen and which contained no separating walls between the nozzles. The crude oil delivered from conduit 3 was atomized by 34 Nm3/h. (or 8.5 Nm.3/h. per nozzle) oxygen introduced from conduit 4. A portion of the atomized oil was reacted with the oxygen under acetylene forming conditions by incomplete combustion to produce gaseous reaction products. v

The unreacted crude oil was removed from the reactor through conduit 5 at the bottom of the reactor and the gaseous reaction products were withdrawn through conduit 6. After separation of the entrainedv oil from the The reactor of the present invention The reactor, illustrated in FIGURE 3a, had a diameter of cm. and a height of 60 cm. In its cover were mounted, as shown in FIGURE 3b, four of the same atomizing nozzles 2, that were used in the reactor described above and illustratedin FIGURES 2a and 2b. The oxygen` was supplied to thenozzles by conduit 4 and was introduced at the rate of 34 Nm.3/h. (or 8.5 Nm.3/h. per nozzle). The crude oil was introduced through the conduit 3, and-the non-reacted oil was removed from the reactor through conduit 5. In this case, each of the atomizng nozzles of the reactor was surrounded vby a cylindrical shield 7, the inner diameter of each shield being mm. and its height being 50 mm. Cooling water was introduced into the shields through conduit 8 and withdrawn through conduit 9. The gaseous lreaction products containing the unsaturated hydrocarbons were removed through conduit 6', and the unreacted crude oil through conduit 5. In this experiment the cross-sectionall-oading of the reactor amounted' to 10.8 Nm3/h. oxygen per dm.2 and the volume loading to 1.8 Nm3/h. oxygen per liter. The oxygen consumption was only 3.2 kg. per kg. of acetylene plus ethylene. After separation of the entrained oil vapors from the gaseous reaction products, the concentration of the desired reaction products in the latter was found to be relatively high, being 7.4% by volume acetylene and 6.2% by volume ethylene. In this experiment the operation of the reactor was quite smooth and stable, without any of the nozzles being ext tingushed and Without the formation of any incrustations, with the result that the reactor could be operated for ex-l tended periods of time without the necessiity of shutting down for cleaning of the nozzles.

The results obtained with the three reactors described above are shown in the following table for comparison purposes. v

Concentration in reacted gasses of:

Aeetylene Ethylene Oxygen consumption per kg. of Aeetyleue plus 5.7 vol. pereeut 7.3 vol. percent. 3.5 vol. pereeut.-.. 6.2 vol. percent. 5.1 kg 2 kg.

6.3 vol. percent. 6.4 vol. pereent 3.3

Ethylene Cross-sectional loading 1.4 Nm, Oz per 2.7 Nm per 10.8 Nm.3 per h and dm.2 h and dm h and dm.2

Volume loading 0.12 Nm, 02 per 0.34 Nm per 1.3 Nm.3 per h and liter. h and liter. h and liter.

gaseous reaction products the latter were found to contain 5.7% by volume acetylene and 3.5% by volume of ethylene, the yield in this case being much less than in the rst reactor where only one atomizer was used. This was clearly shown by the high oxygen consumption of 5.1 kg. per l kg. of acetylene plus ethylene formed. This resulted in greater consumption of crude oil and the production of more undesired carbon monoxide and carbon dioxide. It was found possible to operate this reactor for only relatively short periods of time because of the formation of incrustations about the nozzles to a degree such that certain of the nozzles were obstructed to such an extent that they ceased to operate and for safety reasons it was necessary to `stop the reactor in order to prevent the accumulation of excess oxygen therein. The cross-sectional loading of the reactor was 2.7 Nm3/h. oxygen per dm.2 and the volume loading of 0.34 Nm3/h. oxygen per liter was only slightly higher than with the single-nozzle .reactor described above.

FIGURE 4 shows an especially advantageous form of reactor in which the separating walls between the nozzles are arranged in honeycomb formation with each nozzle at the center of a hexagon. The numeral 1 represents the reactor cover, 2 the location of the shielding walls, and 3 the orifices of the nozzles.

What is claimed is:

1. A reactor for conversion of liquid hydrocarbons to unsaturated hydrocarbons by thermal decomposition under acetylene forming conditions by atomization with an amount of oxygen insuicient for com-plete combustion and quenching the cracking and combustion gases with the same liquid hydrocarbons atomized in excess, which comprises a reactor in the upper portion of which are mounted a plurality of binary atomizing nozzles whose orices are shielded from each other by separating walls, the average distance of which from the said nozzles, expressed in millimeters, is 0.7 to 2.5 times the amount of oxygen released from the nozzle in Nmv/h., and the height of the said separating walls above the level of the nozzle orifices is 0.5 to 5 times its average distance from the surrounding walls.

2. The reactor of claim 1 in which the separating walls are `cooled by a cooling fluid circulating through hollow spaces therein.

3. The reactor of claim 1 in which the separating walls are in honeycomb formation with a single hexagonal chamber at the center. Y

4. The reactor of claim 1 in which the separating Walls are hollow and are arranged in honeycomb formation with a single hexagonal chamber at the center, and means for circulating cooling iluid through hollow spaces in said separating walls.

5. A reactor for conversion of liquid hydrocarbons to unsaturated hydrocarbons by thermal decomposition under acetylene forming conditions by atomization with an `amount of oxygen insuicient for complete combustion and quenching the cracking and `combustion gases with the same liquid hydrocarbons atomized in excess, which cornprises a reactor in the upper portion of which are mounted, a plurality of binary atomizing nozzles whose orices are shielded from each other by separating walls, the average distances of which from the said nozzles, expressed in millimeters, is 0.7 to 2.5 times the amount of oxygen released from the nozzle in Nm3/h., and the height of said separating walls above the level of the nozzle orices is 0.5 to 5 times its average distance from the surrounding Walls, means for introducing into said reactor through said nozzles regulated amounts of liquid hydrocarbons and oxygen, means for removing unreacted hydrocarbons, and means for removing gaseous reaction products.

6. A reactor of claim 5 in which the separating walls contain means for circulating a cooling fluid through the hollow spaces therein.

7. A reactor of claim 5 in which the separating walls are in honeycomb formation with a single hexagonal chamber at the center.

8. A reactor of claim 5 in which the separating walls are hollow yand are arranged in honeycomb formation with a single hexagonal chamber at the center, fand means for circulating cooling fluid through said hollow spaces in said separating walls.

References Cited by the Examiner UNITED STATES PATENTS 1,616,209 2/1927 Weisgarber 196-128 X 1,823,503 9/1931 Mittasch 260-679 1,925,131 9/1933 Brownlee 23-259 X 2,306,818 12/1942 Lyster 196-116 3,026,185 3/1962 Tareyell 23-259.5 3,213,015 10/1965 Atkinson 196-116 X NORMAN YUDKOFF, Primary Examiner.

I. B. DONIHEE, Assistant Examiner. 

1. A REACTOR FOR CONVERSION OF LIQUID HYDROCARBONS TO UNSATURATED HYDROCARBONS BY THERMAL DECOMPOSITION UNDER ACETYLENE FORMING CONDITIONS BY ATOMIZATION WITH AN AMOUNT OF OXYGEN INSUFFICIENT FOR COMPLETE COMBUSTION AND QUENCHING THE CRACKING AND COMBUSTION GASES WITH THE SAME LIQUID HYDROCARBONS ATOMIZED IN EXCESS, WHICH COMPRISES A REACTOR IN THE UPPER PORTION OF WHICH ARE MOUNTED A PLURALITY OF BINARY ATOMIZING NOZZLES WHOSE ORIFICES ARE SHIELDED FROM EACH OTHER BY SEPARATING WALLS, THE AVERAGE DISTANCE OF WHICH FROM THE SAID NOZZLES, EXPRESSED IN MILLIMETERS, IS 0.7 TO 2.5 TIMES THE AMOUNT OF OXYGEN RELEASED FROM THE NOZZLE IN NM.3/H., AND THE HEIGHT OF THE SAID SEPARATING WALLS ABOVE THE LEVEL OF THE NOZZLE ORIFICES IS 0.5 TO 5 TIMES ITS AVERAGE DISTANCE FROM THE SURROUNDING WALLS. 